The present invention relates generally to the field of machines for driving threaded fasteners into workpieces and, more particularly, to machines of the above type which permit automated feeding of the workpieces and driving of headless fasteners.
In the assembly of workpieces, such as furniture legs, spindles, handles, supports, etc. it is often desirable to screw an elongated headless fastener, such as a hangar bolt or dowel screw, into the workpiece. The existing art discloses various devices which are useful for driving fasteners into workpieces, and the following patents are believed generally relevant to the present invention:
______________________________________ U.S. Pat. No. Inventor Issued ______________________________________ 1,863,314 Phelps et al June 14, 1932 2,806,494 Kull Sept. 17, 1957 2,843,166 Van Alstyne July 15, 1958 3,902,537 Donnelli Sept. 2, 1975 4,114,663 Viner Sept. 19, 1978 4,201,255 Donnelli et al May 6, 1980 ______________________________________
U.S. Pat. No. 1,863,314 to Phelps et al. discloses an apparatus for automatically feeding screws having heads from a hopper into a device which inserts the screws into workpieces. The operation and usefulness of the apparatus is different from the present invention in that it does not screw the fastener into the workpiece, but instead pushes the screw laterally into a recess sized for a press fit therewith.
U.S. Pat. No. 4,114,663 to Viner discloses an automatic screwdriver for driving screws into a workpiece. This device is apparently not useful for driving headless fasteners. Moreover, alignment of the screws is not automated, since the gun is manually held and manipulated.
U.S. Pat. No. 2,806,494 to Kull discloses a screw feeding and driving apparatus which employs headless fasteners, in this case hollow set screws. The device is otherwise different than the present invention, notably, there not being disclosed any means for automatically drilling pilot holes into the workpiece as well as a means for automatically feeding the workpiece to the driving station.
U.S. Pat. No. 2,843,166 to Van Alstyne discloses a stud transfer and holding means for a stud driving tool. This device also does not disclose means for automatically drilling pilot holes into the work member or means for automatically feeding and advancing the work members.
U.S. Pat. No. 3,902,537 to Donnelli and U.S. Pat. No. 4,201,255 to Donnelli et al. both disclose means for threading headless fasteners into workpieces. Both devices are notably different from the present invention in that they require manual manipulation of the workpiece to drive the fastener into the workpiece. Further, no means for automatically drilling the pilot holes is disclosed.